<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div >
        <div id="app">
            <!-- v-model是这种写法的  语法糖   -->
            <input type="text" :value='msg' @input='fn1($event)'>
            <button @click='showmsg'>showmsg</button>
        </div>
 
    </div>
    <!-- 开发环境版本，包含了有帮助的命令行警告 -->
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
    <script>
   
        var vm = new Vue({
            // 监管的容器 
            el:'#app',
            // 数据定义
            data:{
                msg:'',
                
            },
            methods:{
                showmsg(){
                    console.log(this.msg)
                },
                fn1(e) {
                    console.log('fn1')
                    this.msg = e.target.value
                }
            }
        })
     
        console.log('vm',vm)

      

    </script>
</body>

</html>